The year has brought music-lovers some fascinating shifts in what they listen to — and how — and also set off some flares about what the next decade might sound like. Here are a few key trends from 2011:

The ukulele revival: Once associated with Tiny Tim and other novelty artists, the pint-size stringed instrument has enjoyed a serious revival in recent years, thanks to the patronage of some high-profile artists. Pearl Jam’s Eddie Vedder devoted an entire album to it this year with the solo release “Ukulele Songs,” Paul McCartney broke one out during his stadium concerts to pay tribute to his old pal George Harrison (himself a uke devotee), and much-praised indie rocker Merrill Garbus of Tune-Yards rocked one at her concerts and on her acclaimed “Whokill” album.

The cutting edge of mellow:Call it what you will — The Revenge of Muzak, Soft Rock Mach II, The John Tesh Revival — mellowness is back. Acts including Justin Vernon’s band Bon Iver, James Blake, Destroyer and Drake sold lots of records and generated gushing reviews with a sound that would’ve been chastised as elevator music in the ’80s: plush keyboards, saxophone solos, tepid beats. Bon Iver’s second, self-titled album topped the year-end lists at influential publications such as Pitchfork and Paste, even though it reminded some listeners of the kind of sentimental mush that used to get laughed at decades ago by acerbic indie-music tastemakers. In any case, the chaotic often took a back seat to the laid-back.

Music in the cloud:Before he died, Apple founder Steve Jobs proclaimed “the end of the PC-centric era of computing.” Now all the media we’ll ever need, including music, are instantly available anywhere we go on cellphones. “The paradise of infinite storage,” as former record producer Sandy Pearlman once called it, is at hand. Music collections are no longer tethered to computer hard drives, let alone antiquated shelves stacked with CDs and vinyl, but in virtual storage lockers accessed by streaming services such as Apple’s iCloud, Amazon’s Cloud Drive, Music Beta by Google and Spotify, which finally debuted in America after clearing numerous licensing hurdles. Bigger questions still loom: Will audio fidelity continue to matter less and less as convenience and portability rule? And is there enough money in streaming services to fairly compensate artists and other copyright-holders?

Protest-music vacuum: Maybe artists don’t feel equipped to write songs about the recession and the Arab Spring just yet, but you would think that the Occupy Wall Street movement might’ve sparked a few protest songs by now. In contrast with the outpouring of musical commentary inspired by America’s invasion of Iraq in 2003 (dozens of outraged songs from R.E.M., the Beastie Boys, Billy Bragg and countless others), iPods aren’t exactly being rocked in 2011 with the sounds of discontent. Not that Rage Against the Machine guitarist Tom Morello didn’t try. He issued a couple of recordings in 2011 that could serve as soundtracks for street rallies (“Union Town” and “World Wide Rebel Songs”). As the turmoil spills over into 2012, maybe more musicians will follow Morello’s lead.

U.S. vs. piracy: Like governments in France and New Zealand, Congress is taking up the fight against rogue file-sharing of digital music and movies. Two bills, one called the “Protect IP (Intellectual Property) Act,” are making their way through the U.S. Senate and House at the moment, both with provisions that would allow license-holders to seek court action to restrain infringing activities by websites. Even with more legitimate websites than ever selling music to consumers at cut-rate prices, business is booming for rogue sites facilitating free access to copyrighted content.

Copyright holders think the legislation is long overdue, but many free-speech and consumer advocates fret that the bills are so broad that they would threaten many legitimate businesses and interactions as well.

The Adele effect:The British singer cut across lines of genre and generation with her second studio album, “21.” Even as Lady Gaga piled on the visual outrage, Katy Perry maintained a steady chart presence with hit after hit and Rihanna seemed to be an obligatory hook-for-hire singer on every single ever released (including recent ones by Coldplay and Drake), Adele transcended them all. She capped the year with six Grammy nominations, and enters the 2012 competition as the favorite to win album of the year, as well as song and record of the year for “Rolling in the Deep.”